Microsoft has released new details on an experimental operating system concept named Drawbridge. In early March Microsoft researchers presented a paper entitled Rethinking the Library OS from the Top Down. The paper describes a new interaction between a user-level application and its OS. The paper can be found at the ACM Digital Library [frustratingly, we can't redistribute the article since it's behind a paywall, like too much of the scientific world]. It describes an ambitious plan to separate the traditional API parts of an OS from the underlying kernel of the OS. But a full analysis requires some background.